Osteoarthritis May Raise Heart Disease Risk

But inactivity, obesity and inflammation could also be playing a role.

12/23/2013 | By Linda Rath

Adults with hip or knee osteoarthritis (OA) may be at increased risk of cardiovascular disease (CVD), according to a new Canadian study. The findings, published in the December Arthritis Care & Research, showed that women and older men with OA are more likely to be hospitalized for heart problems than are those without arthritis. The risk was greatest for patients needing joint replacement surgery. But at least one expert says that it’s not possible to tell from this study if OA is actually the cause of the increased CVD risk.

Lead study author M. Mushfiqur Rahman, a PhD. candidate at the University of British Columbia in Vancouver, says that although rheumatoid arthritis, lupus and other autoimmune forms of arthritis are associated with a higher risk of heart disease, very little is known about its connection with OA, a condition that is far more common.

"To the best of our knowledge, this is the first prospective longitudinal study of the relationship between OA and CVD," he says.

Rahman and his colleagues reasoned that adults with OA might be prone to cardiovascular problems because they are more likely to have risk factors such as inactivity, obesity, chronic inflammation and muscle weakness and to use nonsteroidal anti-inflammatory drugs (NSAIDs) – known to increase the risk of heart attack. NSAIDs include celecoxib, diclofenac, ibuprofen, meloxicam and naproxen.

To test this theory, the researchers selected a sample population from people registered in a large Canadian Ministry of Health administrative database between 1991 and 2009. A total of 12,745 patients with diagnosed OA were matched with nearly 37,000 people who did not have arthritis. Sixty percent were women, the average age was 58 and none had CVD before the study.

In comparing the two groups, researchers took into account factors that could influence heart disease risk, including age, sex, socioeconomic status and health conditions such as high blood pressure, high cholesterol and diabetes. The database did not contain information about body mass index (BMI), so this was estimated using statistics from a large Canadian health survey.

Patients in the study were followed for an average of 13 years and up to 18 years in some cases. In that time, nearly 8,000 were hospitalized for various types of heart disease, including myocardial infarction (heart attack), ischemic heart disease (reduced blood flow to the heart), congestive heart failure (reduced ability to pump blood to the rest of the body) and stroke. Analysis of the data showed having OA increased the risk of hospitalization for CVD in adult women of all ages and in men 65 and older compared with their counterparts who did not have OA.

The estimated increased risk was 23 percent among women younger than 65, 17 percent among older women and 15 percent among older men. No increased risk was seen for men younger than 65. When broken down by diagnosis, the risk of ischemic heart disease and congestive heart failure increased, but not heart attack or stroke.

Adults with hip or knee osteoarthritis (OA) may be at increased risk of cardiovascular disease (CVD), according to a new Canadian study. The findings, published in the December Arthritis Care & Research, showed that women and older men with OA are more likely to be hospitalized for heart problems than are those without arthritis. The risk was greatest for patients needing joint replacement surgery. But at least one expert says that it’s not possible to tell from this study if OA is actually the cause of the increased CVD risk.

Lead study author M. Mushfiqur Rahman, a PhD. candidate at the University of British Columbia in Vancouver, says that although rheumatoid arthritis, lupus and other autoimmune forms of arthritis are associated with a higher risk of heart disease, very little is known about its connection with OA, a condition that is far more common.

"To the best of our knowledge, this is the first prospective longitudinal study of the relationship between OA and CVD," he says.

Rahman and his colleagues reasoned that adults with OA might be prone to cardiovascular problems because they are more likely to have risk factors such as inactivity, obesity, chronic inflammation and muscle weakness and to use nonsteroidal anti-inflammatory drugs (NSAIDs) – known to increase the risk of heart attack. NSAIDs include celecoxib, diclofenac, ibuprofen, meloxicam and naproxen.

To test this theory, the researchers selected a sample population from people registered in a large Canadian Ministry of Health administrative database between 1991 and 2009. A total of 12,745 patients with diagnosed OA were matched with nearly 37,000 people who did not have arthritis. Sixty percent were women, the average age was 58 and none had CVD before the study.

In comparing the two groups, researchers took into account factors that could influence heart disease risk, including age, sex, socioeconomic status and health conditions such as high blood pressure, high cholesterol and diabetes. The database did not contain information about body mass index (BMI), so this was estimated using statistics from a large Canadian health survey.

Patients in the study were followed for an average of 13 years and up to 18 years in some cases. In that time, nearly 8,000 were hospitalized for various types of heart disease, including myocardial infarction (heart attack), ischemic heart disease (reduced blood flow to the heart), congestive heart failure (reduced ability to pump blood to the rest of the body) and stroke. Analysis of the data showed having OA increased the risk of hospitalization for CVD in adult women of all ages and in men 65 and older compared with their counterparts who did not have OA.

The estimated increased risk was 23 percent among women younger than 65, 17 percent among older women and 15 percent among older men. No increased risk was seen for men younger than 65. When broken down by diagnosis, the risk of ischemic heart disease and congestive heart failure increased, but not heart attack or stroke.

Having more severe arthritis – measured by referrals to orthopaedic specialists and joint replacement surgeries – further increased CVD risk. Again, the overall risk was greatest among women.

Researchers aren't quite sure why the discrepancies between men and women exist, though Rahman suggests that differences in the prevalence of OA, which affects more women, and CVD, which affects more men, might play a role.

He adds, "One limitation of our study was that our database did not include records of patients treated at emergency care units. Some deaths from myocardial infarction or stroke that occurred at emergency care units or at home were not captured in our study and this may have caused gender differences in the CVD rates."

Despite this and other limitations, however, he believes the study has laid the groundwork for further research into the link between heart disease and OA.

For now, he says, "The findings can inform both clinicians and patients of the cardiovascular disease risks among men and women with arthritis. Patients should be aware of the adverse impact of factors such as chronic inflammation, obesity and metabolic syndrome [a group of symptoms, including high blood pressure and high cholesterol, that can lead to heart disease and other health problems], reduced physical activity, muscle weakness and NSAID drug use."

David Felson, MD, a professor of medicine and epidemiology at Boston University, agrees wholeheartedly that arthritis patients and their doctors need to understand the importance of physical activity and weight management for reducing pain and disability and improving overall health.

But he also feels the Canadian study is flawed.

He explains, "Unfortunately, people with OA tend to have a lot of other illnesses. Eighty percent have one or more comorbid problems, including high rates of diabetes and co-existent heart disease that are generally part of being older and overweight. To figure out whether OA itself is causing things like cardiovascular mortality, you have to adjust for all those other comorbidities."

He notes, for instance, that researchers didn't have obesity statistics and so had to “impute” – or estimate – them. Because obesity is such a large risk factor for heart disease, not being able to properly control for it is a "fatal flaw."

Another problem is that the severity of comorbidities isn't known – only that patients did or did not have them. "High blood pressure has little effect on mortality if it is relatively low, but if it is high, it has a great effect on the heart," he says. "But we don't know if high blood pressure is worse in OA patients than in non-OA patients, so simply adjusting for its presence or absence [isn't enough]."

Still, he reiterates that people with OA can improve arthritis symptoms and reduce heart disease risk by staying active and managing weight, high blood pressure and other risk factors.